Most conventional lawn-mowers include one or more blades rotatably about a vertical axis in a downwardly-opening casing. Such conventional lawn-mowers require an important amount of energy to cut a given surface of grass of a predetermined height, and the cut grass tends to adhere to the inner surface of the casing, such that cleaning of the casing is frequently required. Moreover, such conventional lawn-mowers require frequent sharpening of the blades, and the latter can be readily damaged by stones or the like present on the lawn. Conventional lawn-mowers cannot cut small diameter trunks, such as bush, and are ineffective in tall grass.
It is known to provide wood chippers used in the wood industries to convert tree trunks and branches into wood chips. Such wood chippers include specially-designed teeth removably fixed at the periphery of a rotor. Each tooth, when damaged or when requiring sharpening, must be individually removed and fixed back to the rotor, a time-consuming operation.
In the snowblower field, a large screw is often used for engaging and conveying the snow to an ejector impeller, this screw being sometimes provided at its peripheral edge with permanently-fixed ice-engaging teeth. Such arrangements are not suitable for cutting grass and the like flexible material.